The self-confessed mass murderer claimed to be a “warrior” and a “soldier” who was saving Europe from disaster, said Geir Lippestad, his lawyer.

Mr Lippestad said he had conceded that people viewed him as a “demon” but claimed they would “understand” why he wanted to become one of the world’s worst serial killers.

Despite admitting the murders and taking police through his actions, he continues to deny committing any crime and had not expressed any remorse for his actions, the lawyer added.

Just over a month ago, Breivik, dressed as a policeman and armed with rifles and pistols, carried out his hour-long massacre, indiscriminately killing members of a youth camp on Utoya, a holiday island 25 miles from Oslo, Norway's capital city.

By the time he had finished, 69 lay dead, nearly half of whom were under the age of 18. The far-right extremist, 32, had earlier set off the bomb in central Oslo, killing eight.

Breivik, in a 1500-page manifesto posted on the internet, criticised Norway's ruling Labour party for supporting Muslim immigration and multiculturalism.

On Tuesday, Mr Lippestad said his client acknowledged that he had done “something dreadful” but that it was “necessary” to stop Europe from failing.

Speaking to the BBC in his Norwegian office, Mr Lippestad suggested that other people “who think the say way as him” were planning other atrocities.

“He explains he has some friends abroad that think the same way as him and that they will continue his work,” he said.

He added that his client continued to view his actions as "necessary".

“He knows he has done something dreadful and he knows that he is being looked upon as a demon,” he said.

“But he explains everything and says it was necessary because if I don’t do this Europe will fail and Europe will fall.

He added: “He says it was necessary for the course and in that context he looks upon himself as a warrior and soldier who has the right case.

“He believes in his head that he has done something right for Europe and starting a war of some kind.”

Mr Lippestad, who admitted he had thought twice about taking on the case, said his client had found it “difficult to sit in isolation” in jail. The prisoner is "calm" but still "living in his own world ... and is not showing remorse".

He said he reads books in jail and is allowed to watch “normal, family” movies chosen by prison officials while also having access to a priest and an “off-line computer”. He is guarded around the clock.

A judge has previously denied the right for Breivik to be removed from solitary confinement.

Breivik told his lawyer that Norwegians would eventually “understand” what he did.

“He knows the people in Norway would look at him as some kind of demon … but he feels people will understand and will look at him in another way,” he added.

Over the past few weeks forensic experts have combed the island to build a picture of the victims' final moments as they tried to hide, flee and even swim to safety.

They brought Breivik back last week to re-enact his massacre to aid their investigation.

A majority of the 517 survivors of the July 22 massacre – 66 of whom were wounded – and their families took part in a memorial service on the island at the weekend.

Having completed their investigation on the island, Norwegian police are scheduled to hand Utoeya back to the Labour Party youth wing early on Tuesday.

Party officials quickly announced after the attack their intention to continue organising summer camps there.

Breivik is expected to remain in solitary confinement until his trial next year.